I know it always supports big business. And it’s a reactionary force that people in power turn to when things go badly for the workers and they think of revolt.
But fascism also demands genocide and killing of millions of people and that would only hurt the capitalists, no? Because these are people who would otherwise be working and increasing profit used to increase productivity etc etc etc. But if you kill them you reduce the labor force and thus drive up the price of labor, reducing your profits, and thus what you can spend on improving productivity? And other countries which didn’t do so would become more advanced, leaving you behind.
I don't know if this is a useful response or not (or even completely correct theory-wise), but my understanding is that capitalists do not innately value profit, the profit motive is simply what drives them under capitalism, because the accumulation of that profit is what gives them the power, status, and physical comfort that they more innately crave as animals.
So, in a hypothetical fascist takeover where even millions of working people are murdered by said fascists to stave off a communist movement, so long as their relative comfort and status are largely preserved, I think capitalists are mostly fine with it.